T12钢盐浴渗铬工艺对渗层组织和性能的影响

采用正交实验方法优化T12钢的低温盐浴渗铬工艺。正交实验表明,以BaCl2-CaCl2为基盐,以Cr2O3 铬盐(Cr3 ) 铬粉 NaF为渗铬剂,在0.15MPa氩气保护下,经850℃×6h渗铬,可获得与基体结合良好的48μm的渗铬层,渗层表面铬浓度约86.9wt%,表面硬度可达1750HV。渗铬表层主要物相为Cr7C3、Cr2C、Cr和(Cr,Fe)2O3组成。渗铬层具有优良耐蚀性,阳极极化曲线的测定分析证明渗铬层的耐腐蚀性能优于1Cr18Ni9Ti不锈钢。     

GCr15钢硼铬共渗层组织与相结构的研究

通过金相显微、扫描电镜能谱、电子探针、X射线衍射分析,探讨了GCr15钢盐浴硼铬共渗层的组织和相组成。结果表明:硼铬共渗层与单渗硼层相似,具有梳齿状特征,但在其渗层外部有一含有较高铬和碳元素的白亮带;共渗层主要是由(Fe,Cr)_2B相组成,此外还有少量的(Cr,Fe)_7(C_2B)_3和(Fe,Cr)_3(C,B)相。     

反应温度及时间对奥氏体不锈钢渗铬层组织结构的影响

利用固体粉末包埋技术对316H奥氏体不锈钢进行了 1090℃保温0.5～20 h和750～1150℃保温10 h的化学热处理,研究了不同工艺参数对渗铬层组织结构和耐磨性的影响.通过光学金相显微镜(OM),扫描电镜(SEM),能谱仪(EDS)以及X射线衍射仪(XRD)等分析手段,研究了保温时间和反应温度对渗铬层的微观组织...     

45钢低温盐浴渗铬工艺及渗层性能研究

研究了 45钢低温盐浴渗铬工艺 ,分析了渗铬层的金相组织和相结构 ,测量了渗层厚度、渗层硬度及铬浓度分布 ,并进行了渗铬层的耐磨试验。结果表明 ,45钢在较低温度盐浴可获得良好的渗铬层及优异的耐磨性。     

45钢低温盐溶渗铬工艺及渗层性能研究

研究了45钢低温盐浴渗铬工艺，分析了渗铬层的金相组织和相结构，测量了渗层厚度、渗层硬度及铬浓度分布，并进行了渗铬层的耐磨试验。结果表明，45钢在较低温度盐浴可获得良好的渗铬层及优异的耐磨性。     

20钢低温盐浴渗铬工艺及性能研究

对20钢试样离子渗氮后在900℃以下进行盐浴渗铬,分析了渗铬层的形成过程、成分、组织和相结构,并对20钢试样离子渗氮以及渗氮后渗铬进行了硬度对比分析.结果表明,渗氮后进行渗铬能有效提高钢件的表面硬度.低温复合渗铬的保温温度的提高能够提高渗铬扩散速度,以获得更大的渗铬层厚度,且在保温6h的条件下获得了最佳渗铬层组织.     

渗铌层的组织与性能研究

采用45~#、T10A等四种钢经固体渗铌处理,通过金相、X射线衍射分析和硬度测量对其渗层动力学影响因素、金相形貌和物相、硬度等进行了研究。结果表明:高碳钢能获得较高的硬度,若碳量较低需进行碳铌共渗或先渗碳再渗铌才能获得较高的硬度。渗铌层是由NbC-Nb_2C和NbFe组成的比合物层。推荐的渗铌可用1050℃×4～6h,催渗剂用CaCl_2,渗层厚度可达0.03～0.05mm。铝热法渗铌的铝量在氧化铌量的15～20%为宜。     

Microstructure and corrosion resistance of simultaneous Al-Fe coating on copper by pack cementation

Simultaneous Al-Fe coatings on copper were prepared by pack cementation to investigate the microstructure and corrosion resistance. The cross-section of prepared specimen was analyzed by scanning electron microscope (SEM) equipped with an energy dispersive X-ray spectrometer (EDS). Then the cross-section of specimen corroded by solution of ferric chloride in ethanol was evaluated using SEM and X-ray diffraction (XRD). The coating consists of an intermetallic layer and an interdiffusion layer, and the thickness of coating layer increases parabolically with holding temperatures from 730 °C to 900 °C. The aluminum content in the coating varies between 7.65 and 4.0% from the surface to the inside layer while the iron content varies between 2 and 0.5%. The coating layer is composed of а-Cu/Al solid solution with a small amount of iron. Alumina formed on the surface of the coating layer during corrosion provides very good protection for the coating layer in the corrosive atmosphere and enhances the corrosion resistance of the coating.     

Morphology, structure and formation mechanism of silicide coating by pack cementation process

The MoSi2 coating on C 103 niobium based alloy was prepared by pack cementation method. The formative mechanism, morphology and structure of coating were investigated. The silicide coating was formed by reactive diffusion obeying parabolic rule during pack cementation process. It is found that the composite structural coating is composed of three inferior layers as follows. The main layer is composed of MoSi2, the two phases＇ transitional layer consists of NbSi2 and a few NbsSi3 and the diffuse layer is composed of NbsSi3. The dense amorphous glass layer formed on the surface at high temperature oxidation circumstance can effectively prevent the diffusion of oxygen into coating.     

WC基硬质合金CVD涂层的组织与性能

利用X射线衍射研究了CP3型硬质合金涂覆 5层 (TiC TiNC TiC TiCN TiN)硬质层的组织 ,用扫描电镜观察了涂层的断口形貌 ,用划痕法测定了涂层与基体的结合力 ,用三点弯曲方法测定了涂覆前后硬质合金的抗弯强度 ,并用Weibull统计方法对其进行了分析。结果表明 :涂层组织由TiC ,TiC0 .2 N0 .8和TiN组成 ,涂层中无发达的柱状晶 ,涂层与基体结合良好 ,涂覆后硬质合金的抗弯强度有所下降 ,但分散性却减小     

在铝合金表面化学镀Ni-W-P的热稳定性及镀层研究

在1060-H12铝合金表面化学沉积得到Ni-W-P三元合金镀层,通过X射线衍射(XRD)、扫描电镜(SEM)等测试手段研究了镀层的组织、相变行为、镀速及其硬度。结果表明:当镀液的pH值在6～11范围内,镀速随pH值增加而增大,在pH值为9时镀速达到9.5μm/h,而后镀速减小;镀层已完全覆盖基体,表面由胞状颗粒组成,大小比较均匀,无明显的缺陷,镀层呈现非晶态;当pH值为8～9时,镀层与基体结合较为牢固,弯曲试验和锉刀试验显示无脱落和起皮现象;热处理温度为380℃,保温时间为2 h时,XRD曲线中有Ni3P衍射峰出现,镀层硬度HV达到峰值约为840,再随着热处理温度增加,其硬度下降。     

PCrNi3Mo钢真空渗铬层的组织与性能

在真空条件下对PCrNi3Mo钢表面进行渗铬处理,采用X射线衍射、扫描电镜、光学显微镜、自动显微硬度仪、干滑动摩擦及电化学腐蚀等手段分析了渗铬层的组织与性能。结果表明,PCrNi3Mo钢在真空渗铬处理后表面形成了一层由Cr₂₃C₆、Cr₇C₃和(Cr,Fe)₇C₃组成的化合物渗层,渗层致密且与基体结合良好。渗层深度、硬度、耐磨性以及耐腐蚀性均随渗铬保温时间的延长而提高。对工件进行12 h保温渗铬后得到的渗铬层厚度约为11 μm,表面硬度为1117.1 HV0.5,磨擦因数最低,其磨损量为0.1225 mg,自腐蚀电流密度比基体降低了2个数量级,综合性能最优。     

AISI 316L表面氮化复合类金刚石涂层的相结构及摩擦学性能

为提高类金刚石涂层与奥氏体不锈钢之间的结合强度,利用等离子体增强化学气相沉积技术分别在未处理和氮化处理的AISI 316L表面沉积类金刚石（DLC）涂层,研究不同沉积温度下DLC及氮化复合DLC涂层的相结构与摩擦学性能。采用X射线衍射仪（XRD）、拉曼光谱仪（Raman）表征涂层的相结构;采用扫描电子显微镜（SEM）观察截面形貌,并用EDS测量氮、碳元素的深度分布;采用纳米压痕仪、摩擦磨损试验机、超景深显微镜、划痕仪检测DLC涂层的摩擦学性能。结果表明：氮化复合DLC涂层的结合力和耐磨性优于DLC涂层;其中100 ℃时,硬度和结合力分别提高25%和175%,综合性能最好。沉积DLC涂层的过程中,氮化层中氮原子因扩散而重新分布,使氮化层的厚度增加,硬度梯度减缓,更有利于基体与DLC涂层间的过渡。     

Structure of Al-modified silicide coatings on an Nb-based ultrahigh temperature alloy prepared by pack cementation techniques

In order to prepare Al-modified silicide coatings on an Nb-based ultrahigh temperature alloy, both a two-stage pack cementation technique and a co-deposition pack cementation technique were employed. The two-stage process included siliconizing a specimen at 1150 °C for 4 h followed by aluminizing it at 800-1000 °C for 4 h. The coating prepared by pack siliconization was composed of a thick (Nb,X)Si₂ (X represents Ti, Cr and Hf elements) outer layer and a thin (Nb,X)₅Si₃ transitional layer; after the siliconized specimens were aluminized at or above 860 °C, a (Nb,Ti)₃Si₅Al₂ phase developed at the surface of the coating, and furthermore, when aluminizing was carried out at 860 °C, a new (Nb,Ti)₂Al layer formed in the coating between the (Nb,X)₅Si₃ layer and the substrate, but when aluminizing was performed at 900-1000 °C, the new layer formed was (Nb,Ti)Al₃. The co-deposition process was carried out by co-depositing Si and Al on specimens at 1000-1150 °C for 8 h under different pack compositions, and it was found that the structure of co-deposition coatings was more evidently affected by co-deposition temperature than pack composition. An Al-modified silicide coating with an outer layer composed of (Nb,Ti)₃Si₅Al₂, (Nb,X)Si₂ and (Nb,Ti)Al₃ was obtained by co-depositing Si and Al at 1050 °C.     

TiCrAlSiCN薄膜微观结构与性能

采用工业化多弧离子镀在H13钢表面制备高硬度、高结合强度和低摩擦耐磨的TiCrAlSiCN硬质薄膜,以便改善H13钢的力学和摩擦学性能。借助扫描电子显微镜、X射线衍射、X射线光电子能谱仪、透射电子显微镜、维氏显微硬度计、膜划痕试验法、摩擦磨损仪对TiCrAlSiCN薄膜的结构特征、力学性能和摩擦磨损性能进行测试与分析。结果表明,TiCrAlSiCN薄膜结构为纳米晶/非晶复合结构。高Si含量的TiCrAlSiCN薄膜200晶面呈择优取向、硬度为3934 HV0.01和2536 HV0.025、摩擦因数为0.65、磨损率为7.36×10-6 mm3·N-1·m-1、膜基结合力为62.4 N。随Si含量降低,Cr和C含量增大,薄膜无明显的择优取向,开始向各向同性转变,硬度为3613 HV0.01和2815 HV0.025、摩擦因数为0.48、磨损率为7.28×10-6 mm3·N-1·m-1、膜基结合力为68.2 N。低Si含量TiCrAlSiCN薄膜力学和摩擦学性能优异。     

Interface reaction between nickel-base self-fluxing alloy coating and steel substrate

The interface reaction between a nickel-base, self-fluxing alloy coating and a steel substrate has been investigated to examine the formation of “pores,” which are observed along the interface of used boiler tubes. It was found that lumpy precipitates form along the interface instead of pores after heating at high temperatures and that the precipitates are of Fe₂B boride. The adhesion strength of the coating is not decreased by the formation of Fe₂B precipitates along the interface because of the increase of the adhesion due to interdiffusion.     

Fabrication and its characteristics of hard coating Ti-Al-N system prepared by DC magnetron sputtering

Pseudobinary Ti1-xAlxN films were synthesized on Si (100) wafer by DC magnetron sputtering method using Ti1-dAlx alloy targets with different Al contents. The composition of the Ti1-AlxN films was determined by electron probe microanalysis (EPMA). Structural characteristic was performed by X-ray diffraction (XRD), transmission electron microscopy (TEM), and high-resolution TEM (HRTEM). First principles virtual crystal calculations for the Ti1-xAlxN disordered alloys were used for the XRD simulations. The crystalline structure of the Ti0. 61Al0. 39N film was found to be a metastable single phase with NaCl (B1) structure. Its lattice constant, determined by XRD, was less than that of pure TiN. With the increase of Al content, the lattice constant of B1 phase was continually decreased, while würtzite (B4) structure was observed in the Ti0. 40Al0. 60N film. When x reached 0. 75, the B1 phase disappeared, and only 34 phase was remained. The critical Al content for the phase transition from NaCl to würtzite structure in this paper was about 0. 60, which could be explained by both the thermodynamic model and the electron theory. As-deposited Ti1-xAlxN films exhibited excellent mechanical properties. Hardness measurements of Ti1-xAlxN films showed a high value of 45GPa for x=0. 39 and was decreased to value of 27 Gpa with increasing Al at x=0. 60.